1. Technical Field
The present disclosure relates to a wrinkle detection apparatus and a wrinkle detection method for detecting a wrinkle area of skin included in an image.
2. Description of the Related Art
Conventionally, a wrinkle area of skin is detected from a photographed face image. The wrinkle area refers to a linear image area of a wrinkle portion shown on the image.
However, the wrinkle area is not detected, or a portion that is not a wrinkle is detected as the wrinkle area in some cases under influence of illumination or the like. Therefore, PTL 1, for example, describes a technique to improve accuracy of detection (hereinafter referred to as “wrinkle detection”) of the wrinkle area from the image.
The technique (hereinafter referred to as “conventional technique”) described in PTL 1 calculates a gradient value in each portion of the image by using an edge detection filter, and obtains a line element from the image by comparing each gradient value with a threshold. Here, the gradient value refers to a value that indicates a degree of change in pixel values in the image. By repeating processing for comparing each gradient value with a lower threshold in a portion adjacent to the obtained line element, the conventional technique expands the area of line element.
As the threshold increases, detection (hereinafter referred to as “misdetection”) of a component other than the wrinkle, such as a chloasma, is reduced. As the threshold decreases, on the other hand, failures to detect the wrinkle that actually exists (hereinafter referred to as “omission of detection”) are reduced.